Volatile copper(II) complexes for deposition of copper films by atomic layer deposition

ABSTRACT

The present invention relates to novel 1,3-diimine copper complexes and the use of 1,3-diimine copper complexes for the deposition of copper on substrates or in or on porous solids in an Atomic Layer Deposition process. This invention also provides a process for making amino-imines and novel amino-imines.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationNo. 60/349,639, filed 18 Jan. 2002.

FIELD OF THE INVENTION

The present invention relates to novel 1,3-diimine copper complexes andthe use of 1,3-diimine copper complexes for the deposition of copper onsubstrates or in or on porous solids in an Atomic Layer Depositionprocess. This invention also provides a process for making amino-iminesand novel amino-imines.

TECHNICAL BACKGROUND

The ALD (Atomic Layer Deposition) process is useful for the creation ofthin films, as described by M. Ritala and M. Leskela in “Atomic LayerDeposition” in Handbook of Thin Film Materials, H. S. Nalwa, Editor,Academic Press, San Diego, 2001, Volume 1, Chapter 2. Such films,especially metal and metal oxide films, are critical components in themanufacture of electronic circuits and devices.

In an ALD process for depositing copper films, a copper precursor andreducing agent are alternatively introduced into a reaction chamber.After the copper precursor is introduced into the reaction chamber andallowed to adsorb onto a substrate, the excess (unabsorbed) precursorvapor is pumped or purged from the chamber. This is followed byintroduction of a reducing agent that reacts with the copper precursorto form copper metal and a free form of the ligand. This cycle can berepeated if needed to achieve the desired film thickness.

This process differs from chemical vapor deposition (CVD) in thedecomposition chemistry of the metal complex. In a CVD process, thecomplex decomposes on contact with the surface to give the desired film.In an ALD process, the complex is not decomposed on contact with thesurface. Rather, formation of the film takes place on introduction of asecond reagent, which reacts with the deposited metal complex. In thepreparation of a copper film from a copper(II) complex, the secondreagent is a reducing agent.

To be useful in an ALD process, the copper complex must be volatileenough to be sublimed without thermal decomposition. Typically,trifluoromethyl group-containing ligands have been used to increase thevolatility of the copper complexes. However this approach has drawbacksin the preparation of interconnect layers, since halides adverselyaffect the properties of the interconnect layer.

The ligands used in the ALD processes must also be stable with respectto decomposition and be able to desorb from the complex in a metal-freeform. Following reduction of the copper, the ligand is liberated andmust be removed from the surface to prevent its incorporation into themetal layer being formed.

U.S. Pat. No. 5,464,666 describes the decomposition of 1,3-diiminecopper complexes in the presence of hydrogen to form copper. This patentalso describes the use of 1,3-diimine copper complexes in a ChemicalVapor Deposition process for producing copper-aluminum alloys.

DE 4202889 describes the use of 1,3-diimine metal complexes to depositcoatings, preferably via a Chemical Vapor Deposition process.Decomposition of the metal complexes in a reducing atmosphere,preferably hydrogen, is disclosed.

S. G. McGeachin, Canadian Journal of Chemistry, 46, 1903-1912 (1968),describes the synthesis of 1,3-diimines and metal complexes of suchligands.

N. A. Domnin and S. I. Yakimovich, Zh. Organ. Khim, 1965, 1(4), 658,describe the reaction of aliphatic beta-diketones with unsymmetricalN,N-dialkylhydrazines to produce bis(dialkylhydrazones).

SUMMARY OF THE INVENTION

This invention describes a process for forming copper deposits on asubstrate comprising:

-   a. contacting a substrate with a copper complex, (I), to form a    deposit of the copper complex on the substrate; and-   b. contacting the deposited copper complex with a reducing agent,    wherein-   R¹ and R⁴ are independently selected from the group consisting of H,    C₁-C₅ alkyl, and dimethylamino;-   R² and R³ are independently selected from the group consisting of H,    C₁-C₅ alkyl, phenyl, benzyl, and 4-pyridinyl, with the proviso that    the total number of carbons in R¹-R⁴ is 4-12; and-   the reducing agent is selected from the group consisting of 9-BBN,    borane, dihydrobenzofuran, pyrazoline, diethylsilane,    dimethylsilane, ethylsilane, methylsilane, phenylsilane and silane.

In another embodiment, this invention provides a 1,3-diimine coppercomplex, (II),

wherein

-   R⁵ and R⁸ are dimethylamino; and

R⁶ and R⁷ are independently selected from the group consisting of H,C₁-C₅ alkyl, phenyl, benzyl, and 4-pyridinyl, with the proviso that thetotal number of carbons in R⁵-R⁸ is 4-14; or

-   R⁵ and R⁸ are independently selected from the group consisting of H,    C₁-C₅ alkyl, and dimethylamino; and-   R⁶ and R⁷ are selected from the group consisting of H, C₁-C₅ alkyl,    phenyl, benzyl, and 4-pyridinyl, with the proviso that either R⁶ or    R⁷ is 4-pyridinyl, and the proviso that the total number of carbons    in R⁵-R⁸ is 4-14.

In another embodiment, this invention provides an article comprising the1,3-diimine copper complexes, (II), deposited on a substrate.

In another embodiment, this invention provides a process for thesynthesis of diimines comprising:

-   a. contacting an alkylimino-monoketone, (III), with an alkylating    agent to form the corresponding O-alkylated derivative, (IV);-   b. contacting the O-alkylated derivative, (IV), of step (a) with a    primary alkyl amine, NH₂R¹³, to form an immonium salt, (V); and-   c. contacting the immonium salt, (V), of step (b) with a strong base    to form the corresponding neutral amino-imine (VI):    wherein-   R¹⁰ and R¹¹ are independently selected from the group consisting of    H, C₁-C₅ alkyl, phenyl, benzyl, and 4-pyridinyl;-   R¹² is Me or Et;-   R⁹ and R¹³ are independently selected from the group consisting of H    and C₁-C₅ alkyl, with the proviso that the total number of carbons    in R⁹, R¹⁰, R¹¹ and R¹³ is 4-12;-   the alkylating agent is selected from the group consisting of    dimethyl sulfate, methyl benzenesulfonate, methyltoluenesulfonate,    diethyl sulfate, ethylbenzenesulfonate,    methyltrifluoromethanesulfonate and ethyl toluenesulfonate; and-   X⁻ is an anion derived from the alkylating agent.

In another embodiment, this invention provides novel amino-imines,

(VII), wherein

-   R¹⁴ and R¹⁷ are independently selected from the group consisting of    H, C₁-C₅ alkyl, and dimethylamino; and-   R¹⁵ and R¹⁶ are selected from the group consisting of H, C₁-C₅    alkyl, phenyl, benzyl, and 4-pyridinyl, with the proviso that either    R¹⁵ or R¹⁶ is 4-pyridinyl and the proviso that the total number of    carbons in R¹⁴-R¹⁷ is 4-14.

DETAILED DESCRIPTION

Applicants have discovered an atomic layer deposition (ALD) processsuitable for creation of copper films for use as seed layers in theformation of copper interconnects in integrated circuits, or for use indecorative or catalytic applications. This process uses copper(II)complexes that are volatile, thermally stable and derived from ligandswhich contain only C, H, and N. The ligands are chosen to formcopper(II) complexes that are volatile in an appropriate temperaturerange but do not decompose in this temperature range; rather, thecomplexes decompose to metal on addition of a suitable reducing agent.The ligands are further chosen so that they will desorb withoutdecomposition upon exposure to a reducing agent. The reduction of thesecopper complexes to copper metal by readily available reducing agentshas been demonstrated to proceed cleanly at moderate temperatures.

In the process of this invention, copper is deposited on a substrate bymeans of:

-   a. contacting a substrate with a copper complex, (I), to form a    deposit of the copper complex on the substrate; and-   b. contacting the deposited copper complex with a reducing agent,    wherein-   R¹ and R⁴ are independently selected from the group consisting of H,    C₁-C₅ alkyl, and dimethylamino;-   R² and R³ are independently selected from the group consisting of H,    C₁-C₅ alkyl, phenyl, benzyl, and 4-pyridinyl, with the proviso that    the total number of carbons in R¹-R⁴ is 4-12; and-   the reducing agent is selected from the group consisting of 9-BBN,    borane, dihydrobenzofuran, pyrazoline, diethylsilane,    dimethylsilane, ethylsilane, phenylsilane and silane.

The deposition process of this invention improves upon the processesdescribed in the art by allowing for lower temperatures and producingmore uniform films.

In the copper deposition process of this invention, the copper can bedeposited on the surface, or in or on porosity, of the substrate.Suitable substrates include copper, silicon wafers, wafers used in themanufacture of ultra large scale integrated circuit, wafers preparedwith dielectric material having a lower dielectric constant than silicondioxide, and silicon dioxide and low k substrates coated with a barrierlayer. Barrier layers to prevent the migration of copper includetantalum, tantalum nitride, titanium, titanium nitride, tantalum siliconnitride, titanium silicon nitride, tantalum carbon nitride, and niobiumnitride.

This process can be conducted in solution, i.e., by contacting asolution of the copper complex with the reducing agent. However, it ispreferred to expose the substrate to a vapor of the copper complex, andthen remove any excess copper complex (i.e., undeposited complex) byvacuum or purging before exposing the deposited complex to a vapor ofthe reducing agent. After reduction of the copper complex, the free formof the ligand can be removed via vacuum, purging, heating, rinsing witha suitable solvent, or a combination of such steps.

This process can be repeated to build up thicker layers of copper, or toeliminate pin-holes.

The deposition of the copper complex is typically conducted at 0 to 120°C. The reduction of the copper complex is typically carried out atsimilar temperatures, 0 to 120° C.

Aggressive reducing agents are needed to reduce the copper complexrapidly and completely. Reducing agents must be volatile and notdecompose on heating. They must also be of sufficient reducing power toreact rapidly on contact with the copper complex deposited on the coppersurface. A group of suitable reducing agents have been identified thathave not previously been used for copper(II) reduction in an ALDprocess. One feature of these reagents is the presence of a protondonor. The reagent must be able to transfer at least one electron toreduce the copper ion of the complex and at least one proton toprotonate the ligand. The oxidized reducing agent and the protonatedligand must then be easily removed from the surface of the newly formedcopper deposit.

Suitable reducing agents for the copper deposition process of thisinvention include 9-BBN, borane, dihydrobenzofuran, pyrazoline,diethylsilane, dimethylsilane, ethylsilane, phenylsilane and silane.Diethylsilane and silane are preferred.

In a commercial embodiment of the copper deposition process, the coppercomplexes are added to a reactor under conditions of temperature, timeand pressure to attain a suitable fluence of complex to the surface ofthe substrate. One of skill in the art will appreciate that theselection of these variables will depend on individual chamber andsystem design and the desired process rate. After deposition on thesubstrate (e.g., a coated silicon wafer), the complex vapor is pumped orpurged from the chamber and the reducing agent is introduced into thechamber at a pressure of approximately 50 to 760 mTorr to reduce theadsorbed copper complex. The substrate is held at a temperature betweenapproximately 0 to 120° C. during reduction. This reaction must be rapidand complete. Reducing agent exposure times may be from less than asecond to several minutes. The products from this reaction must thenleave the surface. The preferred reagents are the copper 1,3-diiminecomplex (I, wherein R¹, R³, and R⁴ are Me, and R² is phenyl) anddiethylsilane.

The copper(II) complexes useful in the copper deposition process of thisinvention fall into two categories: those with symmetrical ligands(R¹=R⁴ and R²=R³) and those with unsymmetrical ligands (R¹R⁴ and/orR²R³). The copper(II) complexes with symmetrical ligands are solids thatshow good volatility and stability. The preferred ligand from this groupis the N,N′-diethyl derivative, in which R¹=R⁴=Et and R²=R³=Me. However,the unsymmetrical ligands tend to give more volatile complexes, asindicated by the lower sublimation temperature. For example, thesymmetrical N,N′-diethyl derivative can be sublimed at 45 to 50° C. at100 mTorr pressure, whereas the N-methyl-N′-ethyl derivative (R¹=Et andR²=R³=R⁴=Me) sublimes at ca. 25° C. at 100 mTorr. The unsymmetricalcomplexes can be used at a lower operating temperature than thosederived from symmetrical ligands, helping to avoid adverse reactionssuch as decomposition of the copper complex.

In another embodiment, this invention provides novel 1,3-diimine coppercomplexes, (II),

wherein

-   R⁵ and R⁸ are dimethylamino; and-   R⁶ and R⁷ are independently selected from the group consisting of H,    C₁-C₅ alkyl, phenyl, benzyl, and 4-pyridinyl, with the proviso that    the total number of carbons in R⁵-R⁸ is 4-14; or-   R⁵ and R⁸ are independently selected from the group consisting of H,    C₁-C₅ alkyl, and dimethylamino; and-   R⁶ and R⁷ are selected from the group consisting of H, C₁-C₅ alkyl,    phenyl, benzyl, and 4-pyridinyl, with the proviso that either R⁶ or    R⁷ is 4-pyridinyl, and the proviso that the total number of carbons    in R⁵-R⁸ is 4-14.

The novel copper complexes, (II), are useful in the copper depositionprocess of this invention. Preferably, R⁵ and R⁸ are dimethylamino, andR⁶ and R⁷ are C₁-C₅ alkyl, with the proviso that the total number ofcarbons in R⁵-R⁸ is 5-10.

In another embodiment, this invention provides an article comprising1,3-diimine copper complexes, (II), deposited on a substrate such as:copper, silicon wafers, wafers used in the manufacture of ultra largescale integrated circuits, wafers prepared with dielectric materialhaving a lower dielectric constant than silicon dioxide, and silicondioxide and low k substrates coated with a barrier layer. Barrier layersto prevent the migration of copper include tantalum, tantalum nitride,titanium, titanium nitride, tantalum silicon nitride, titanium siliconnitride, tantalum carbon nitride, and niobium nitride.

A new synthetic method for the preparation of amino-imines (precursorsto 1,3-diimine ligands) has also been discovered by the Applicants. Theliterature procedure described by McGeachin requires use of anexpensive, unstable alkylating agent (triethyl oxoniumtetrafluoroborate). A more practical, commercially scalable process mustproceed with high yields and use stable, lower cost reagents. Applicantshave found that dimethylsulfate and other inexpensive alkylatingreagents can be used in place of the triethyl oxonium tetrafluoroboratesalt. These alkylating agents yield the desired amino-imines in highyield, as shown in the examples below. The present process also improvesupon the processes described in the art by not requiring a co-solvent,and simplifying the isolation of the desired product.

Applicants' process for the synthesis of amino-imines comprises:

-   a. contacting an alkylimino-monoketone, (III), with an alkylating    agent to form the corresponding O-alkylated derivative, (IV);-   b. contacting the O-alkylated derivative, (IV), of step (a) with a    primary alkyl amine, NH₂R¹³, to form an immonium salt, (V); and-   c. contacting the immonium salt, (V), of step (b) with a strong base    to form the corresponding neutral amino-imine (VI):    wherein-   R¹⁰ and R¹¹ are independently selected from the group consisting of    H, C₁-C₅ alkyl, phenyl, benzyl, and 4-pyridinyl;-   R¹² is Me or Et;-   R⁹ and R¹³ are independently selected from the group consisting of H    and C₁-C₅ alkyl, with the proviso that the total number of carbons    in R⁹, R¹⁰, R¹¹ and R¹³ is 4-12;-   the alkylating agent is selected from the group consisting of    dimethyl sulfate, methyl benzenesulfonate, methyltoluenesulfonate,    diethyl sulfate, ethylbenzenesulfonate,    methyltrifluoromethanesulfonate and ethyl toluenesulfonate; and-   X⁻ is an anion derived from the alkylating agent.

In the above process for preparing amino-imines, thealkyl-imino-monoketones, (III), are readily available from the reactionof the β-diketones with amines. The preferred primary alkyl amine,NH₂R¹³, is selected from the group consisting of methylamine,ethylamine, and propylamine. The strong base is selected from the groupconsisting of sodium methoxide, copper methoxide, and potassiumtert-butoxide.

In another embodiment, this invention provides novel amino-imines,

(VII), wherein

-   R¹⁴ and R¹⁷ are independently selected from the group consisting of    H, C₁-C₅ alkyl, and dimethylamino; and-   R¹⁵ and R¹⁶ are selected from the group consisting of H, C₁-C₅    alkyl, phenyl, benzyl, and 4-pyridinyl, with the proviso that either    R¹⁵ or R¹⁶ is 4-pyridinyl, and the proviso that the total number of    carbons in R¹⁴-R¹⁷ is 4-14.

Preferably, R¹⁴ and R¹⁷ are dimethylamino, and R¹⁵ and R¹⁶ are C₁-C₄alkyl; or R¹⁵ is 4-pyridinyl and R¹⁴, R¹⁶ and R¹⁷ are C₁-C₄ alkyl.

The amino-imines, (VII), wherein R¹⁴ and R¹⁷ are independently selectedfrom the group consisting of H, C₁-C₅ alkyl, can be made by the processfor making such ligand precursors, as described above. The preparationof amino-imines wherein R¹⁴ and R¹⁷ are dimethylamino and R¹⁵ and R¹⁶are methyl is given in Example 7; analogous dimethylamino ligands withother R¹⁵ and R¹⁶ substituents can be similarly prepared.

EXAMPLES

All organic reagents are available from Sigma-Aldrich, 940 W. St. PaulAvenue, Milwaukee, Wis., USA). Copper ethoxide was purchased from AlfaAesar (30 Bond Street, Ward Hill, Mass., USA).

Example 1 Preparation and Reduction ofBis(N-ethyl-4-ethylimino-2-pentene-2-aminato)copper(II)

The 1,3-diimine ligand, CH₃CH₂N═C(CH₃)—CH₂—C(CH₃)═N—CH₂CH₃.HBF₄, wasprepared according to a literature procedure (McGeachin). The Cu(II)complex was prepared by reaction of the free base with copper(II)methoxide in methanol. Copper methoxide (0.268 g) was weighed into a50-mL Erlenmeyer flask. A magnetic stir bar and 5 mL methanol wereadded. The free ligand was prepared from the tetrafluoroborate salt(1.00 g) by reaction with sodium methoxide; the methoxide solution wasprepared by adding NaH (0.105 g) slowly to 5 mL methanol. This methanolsolution was added all at once to the rapidly stirred copper methoxidesolution along with an additional 5 mL methanol. A purple solutionformed immediately. The mixture was stirred for 1 hour at roomtemperature. Solvent was removed under vacuum. The resulting solid wasmixed with hexane; the resulting mixture was filtered through a sinteredglass frit with a bed of Celite 545. The cake was washed with hexaneuntil the purple color was no longer visible. The solvent was strippedunder vacuum. Sublimation at ca. 100 mTorr pressure and temperaturerange of 40-115° C. yielded a solid with a melting point of 98-100° C. Asample of this material (ca. 0250 g) was sublimed at 70-80° C. at about100 mTorr pressure onto a glass cold finger cooled with Dry Ice. Apurple film was obtained on the glass surface. After cooling, the kettlecontaining the copper complex was replaced with one containingdiethylsilane. The apparatus was heated under vacuum at 50° C. Thepurple color of the copper complex faded to white and then to a faintcopper color, indicating reduction of the starting copper complex tometal.

Example 2 Preparation of MeC(NHMe)═CHC(═O)Me

Aqueous methylamine (100 g, 40% in water) was added, drop-wise, to 100 g2,4-pentanedione. The addition was mildly exothermic; the addition ratewas adjusted to keep the temperature between about 35 and 40° C. Afterthe addition was complete, the resulting yellow liquid was stirred 1 hrat room temperature, then subjected to vacuum distillation. The stillpot was heated under partial vacuum, such that the first distillationcut (presumably water) came over at 30-35° C. After this fraction wasremoved, the distillation was discontinued. The contents of the potsolidified upon cooling. By NMR analysis, the title compound wasobtained (>95% purity) and in good yield (>90%).

Example 3 Preparation of [MeC(NHMe)═CHC(OMe)Me][MeOSO₃]

In the drybox, 4-(methylamino)-3-pentene-2-one (1.00 g) from Example 2was dissolved in CH₂Cl₂ (2 mL) and was mixed with dimethylsulfate (1.00g). The mixture initially formed a yellow solution, cool to the touch,but over the course of an hour, made a thick slurry with some warming.The slurry was filtered and the solids rinsed with CH₂Cl₂, with anisolated yield of 0.90 g (47%, based on dimethylsulfate). The NMR of thesolid product was consistent with title compound.

In the drybox, 4-(methylamino)-3-pentene-2-one (1.08 g) was mixed withCH₂Cl₂ (0.5 mL) and the slurry combined with dimethylsulfate (1.00 g).The resulting solution was initially cool to the touch but over thecourse of an hour it solidified, becoming warm to the touch. Thismixture was allowed to stand overnight on the stir plate at ambienttemperature, then used for the subsequent reaction below. The in situyield is nearly quantitative based on NMR analysis.

Example 4 Preparation of [MeC(NHMe)═CHC(NHEt)Me][MeOSO₃]

The solidified mixture of [MeC(NHMe)═CHC(OMe)Me][MeOSO₃],dichloromethane, and unreacted excess MeC(NHMe)═CHC(═O)Me, prepared bythe method in Example 9, was treated first with 2 ml THF then with 6 mlethylamine (2M ethylamine in tetrahydrofuran). The resulting slurry wasstirred 15 min at stir plate temperature (about 30° C.), then filteredand dried to yield 1.63 g off-white solids. NMR is consistent with thetitle composition present as several tautomers, but absolute purity wasnot established. Crude overall isolated yield for the title compositionis 81%, based on dimethylsulfate.

Example 5 Preparation ofBis(N-methyl-4-ethylimino-2-pentene-2-aminato)copper(II)

The 1,3-diimine [MeC(NHMe)═CHC(NHEt)Me][MeOSO₃], (1.6 g, prepared asdescribed in Example 4) was dissolved in 15 ml methanol. With stirring,potassium t-butoxide (0.71 g) was added. A white precipitate formedimmediately and was removed by filtration after stirring 15 min at roomtemperature. The white precipitate has a ¹H NMR spectrum [D₂O]consistent with K[MeOSO₃]. The filtered solution was treated withCu(OCH₃)₂ (0.40 g). The resulting purple slurry stirred overnight atroom temperature. The solvent was removed, the residue was extractedinto hexane, and insoluble material removed by filtration. The hexanewas removed by evaporation to leave the title compound as an impurepurple paste. The material was purified by sublimation under vacuum (ca.0.02 torr) at room temperature onto a Dry-Ice-cooled glass surface, orat elevated temperature (ca. 100° C.) onto a room-temperature glasssurface.

Example 6 Evaluation of Reducing Agents with Copper(II) 1,3-DiimineComplex

In a dry box, the selected reducing agent (10 equivalents) was addeddrop-wise (via syringe) to a deep purple solution of the copper complexdescribed in Example 1 (ca. 7-16 mg in 5 mL toluene). The reactionmixture was gradually heated from room temperature to 100° C. If therewas no observable change, an additional 10 equivalents of reducing agentwere added at 100° C.

-   -   a) 9-BBN (0.5M solution in THF). The deep purple solution turned        grey/black with heating at 80° C. A black precipitate eventually        settled. The black precipitated indicates formation of small        copper particles.    -   b) Borane (1M solution in THF). The deep purple solution        immediately became clear, then tan/brown, followed by        gray/green. With slight heating at 45° C., the solution turned        black. Eventually, a black precipitate formed.    -   c) Dihydrobenzofuran. The deep purple solution became darker        upon heating at 100° C. An additional 10 equivalent was added        and the solution gradually became a dark copper-colored solution        with a tan precipitate.    -   d) Pyrazoline. Upon heating, the deep purple solution gradually        turned blue, then green/grey (77° C.), then green/copper color        (85° C.), and finally yellow (100° C.). A tan precipitate        formed.    -   e) Diethylsilane. Upon heating (70-80° C.), a black ring formed        on the vial followed by a fine copper-colored mirror. A black        precipitate was observed.

Example 7 Preparation ofBis(N-dimethylamino-4-dimethylaminoimino-2-pentene-2-aminato)copper(II)

A mixture of 4.0 g pentane-2,4-dione and 6.0 g N,N-dimethylhydrazine wasstirred overnight at ambient temperature. The liquid was thenvacuum-distilled at a pressure such that the main distillate wascollected at 89-90° C. Then 0.92 g of this distillate was mixed with0.31 g copper(II) methoxide in 5 ml methanol and stirred for 3 days atambient temperature. The solution was filtered and then evaporated to apurple oil, soluble in hexane and sublimable (ca. 100° C., 0.015 torr).

Example 8 Preparation and Reduction ofBis(N-methyl-4-methylimino-4-phenyl-2-butene-2-aminato)copper(II)

The 1,3-diimine ligand, CH₃N═C(CH₃)—CH₂—C(C₆H₅)═N—CH₃.HBF₄, was preparedaccording to a literature procedure (McGeachin). The Cu(II) complex wasprepared by reaction of the free base with copper(II) ethoxide intetrahydrofuran; the free base was prepared by reaction of thetetrafluoroborate salt with sodium methoxide (Example 1). Copperethoxide (0.408 g) was weighed into a 50-mL flask. A magnetic stir barand ca. 30 mL were added. The free base ligand (1.00 g) in several mLtetrahydrofuran was added all at once to the rapidly stirred copperethoxide solution. A purple solution formed immediately. The mixture wasstirred overnight at room temperature and was then filtered through asintered glass frit with a bed of Celite 545. The solvent was strippedunder vacuum until a dry solid was obtained. Sublimation at ca. 100mtorr pressure and temperature range of 110-120° C. yielded a solid witha melting point of 98-100° C.

The copper(II) complex (0.018 g) was placed in a vial, which was thenplaced in a tube. The tube was heated to 165° C. with a nitrogen gasflow (inlet pressure at 5 torr); the exit pressure from the tube was 30mTorr or less. A second zone in the tube (toward the exit from the tube)was maintained at 100° C. The copper sample sublimed from the initialzone and deposited in the cooler zone, as evidenced by the purpledeposit on the walls of the tube. The apparatus was evacuated and thenback-filled with diethylsilane. A copper deposit formed on the glasswalls in the 100° C. zone, as evidenced by the disappearance of thepurple color and the development of a copper-colored deposit.

Example 9 Preparation of N,N′-Diethyl-2,4-pentanediketimine

In the drybox, a 250 mL round bottom flask was charged with4-(ethylamino)-3-pentene-2-one (30.0 g, 237 mmole) and dimethylsulfate(30.0 g, 238 mmole). The reaction solution was stirred then let stand(12 h) to give a viscous oil. A 2M solution of ethylamine in THF (150mL) was added with vigorous stirring. The solution was stirred (1 h)until it solidified. The intermediate salt can be isolated (as describedby the method in Example 4) or used directly.

A solution of NaOMe (12.8 g, 237 mmole) in MeOH (40 mL) was added to theintermediate salt (vida supra) and let stir (1 h) at ambienttemperature. The solvent was removed (in vacuo) to give an oil that wasextracted with pentane, filtered and concentrated to give a crude yellowoil. The product, N,N′-diethyl-2,4-pentanediketimine, was isolated byfractional distillation to give a yellow oil (28.6 g) in 72% yield basedon the starting 4-(ethylamino)-3-pentene-2-one.

1. A process for forming copper deposits on a substrate comprising: a.contacting a substrate with a copper complex, (I), to form a deposit ofthe copper complex on the substrate; and

b. contacting the deposited copper complex with a reducing agent,wherein R¹ and R⁴ are independently selected from the group consistingof H, C₁-C₅ alkyl, and dimethylamino; R² and R³ are independentlyselected from the group consisting of H, C₁-C₅ alkyl, phenyl, benzyl,and 4-pyridinyl, with the proviso that the total number of carbons inR¹-R⁴ is 4-12; and the reducing agent is selected from the groupconsisting of 9-BBN, borane, dihydrobenzofuran, pyrazoline,diethylsilane, dimethylsilane, ethylsilane, methylsilane, phenylsilaneand silane.
 2. The process of claim 1, wherein R¹, R³ and R⁴ are methyland R² is phenyl.
 3. The process of claim 1, wherein the substrate isselected from the group consisting of copper, silicon wafers and silicondioxide coated with a barrier layer.
 4. The process of claim 1, whereinthe substrate is exposed to a vapor of the copper complex.
 5. Theprocess of claim 1, wherein the deposition is carried out at 0 to 120°C.
 6. The process of claim 1, wherein the reducing agent is silane ordiethylsilane.
 7. A 1,3-diimine copper complex, (II),

wherein R⁵ and R⁸ are dimethylamino; and R⁶ and R⁷ are independentlyselected from the group consisting of H, C₁-C₅ alkyl, phenyl, benzyl,and 4-pyridinyl, with the proviso that the total number of carbons inR⁵-R⁸ is 4-14; or R⁵ and R⁸ are independently selected from the groupconsisting of H, C₁-C₅ alkyl, and dimethylamino; and R⁶ and R⁷ areselected from the group consisting of H, C₁-C₅ alkyl, phenyl, benzyl,and 4-pyridinyl, with the proviso that either R⁶ or R⁷ is 4-pyridinyl,and the proviso that the total number of carbons in R⁵-R⁸ is 4-14.